Upcycling Low-Density Polyethylene Waste into Functional Carbon Anodes for Sodium-Ion Batteries

Plastics waste is a growing concern for humanity, due to its significant environmental impact. This work focuses on repurposing single-use plastic, specifically low-density polyethylene (LDPE), and redirecting it from landfills towards a second-life application in sodium-ion batteries (SIBs). Through sulfonation and pyrolysis (at varying temperatures: 600 °C, 800 °C and 1000 °C), LDPE derived carbon is prepared and examined as an anode material for SIBs. The LDPE derived carbon was first tested in a half-cell and delivered reversible capacities at the 100^th cycle of 171, 211, and 218 mAh g⁻¹ for the materials prepared at 600 °C, 800 °C and 1000 °C, respectively, with each material capable of stable cycling up to 1000 cycles. The most promising material, (1000 °C) was tested in a full-cell configuration, with and without an additional pre-sodiation step. The unmodified full-cell had a reversible capacity of approximately 60 mAh g⁻¹ (based off cathode weight) in comparison to 100 mAh g⁻¹ with pre-sodiation. This study demonstrates a potential second-life application of single-use plastics within the energy sector.